The impact of cardiac resynchronization therapy on the incidence of ventricular arrhythmias in mild heart failure.

<bold>Background: </bold>Cardiac resynchronization therapy (CRT) decreases mortality, improves functional status, and induces reverse left ventricular (LV) remodeling in selected populations. However, the effect of CRT on ventricular arrhythmias is controversial. This is particularly important among patients with mild heart failure (HF), in whom sudden death is a leading cause of mortality.<bold>Objective: </bold>This study sought to assess the impact of CRT on ventricular arrhythmias in mild HF.<bold>Methods: </bold>The REsynchronization reVErses Remodeling in Systolic left vEntricular dysfunction (REVERSE) study is a multicenter randomized, double-blind trial of CRT among patients with mild systolic HF. The time to first appropriate, treated ventricular tachycardia/ventricular fibrillation (VT/VF) episode or spontaneous sustained VT in cardiac resynchronization therapy plus defibrillation device (CRT-D) patients was compared between groups, as were predictors of VT/VF.<bold>Results: </bold>The study randomized 508 patients who received CRT-D devices. There were no significant demographic differences between groups. There were no differences in VT/VF episodes or VT storm between groups. Specifically, in the CRT ON group, the estimated event rate was 18.7% at 2 years, compared with 21.9% in the CRT OFF group (hazard ratio 1.05, P = .84). However, among CRT ON patients, those with reverse remodeling had a reduced incidence of VT/VF compared with those without remodeling (5.6% vs. 16.3%, hazard ratio 0.31, P = .001).<bold>Conclusion: </bold>CRT for up to 2 years does not impact VT/VF in mild HF despite marked clinical and remodeling effects of pacing. This neutral effect may be attributable to competing antiarrhythmic effects of reverse remodeling and proarrhythmic effect of pacing.<bold>Clinical Trial Registration: </bold>http://www.clinicaltrials.gov/ct2/show/NCT00271154. [ABSTRACT FROM AUTHOR]